It is known from, for example, my U.K. Patent Specification No. 1250110 to provide fastening means comprising a nut or bolthead and a spanner component, the nut or bolthead having a smooth edge surface and the spanner component having locating pins adapted to engage in co-operating bores in the nut or bolthead to rotate the nut or bolthead. Such fastening means are referred to hereinafter as "fastening means of the kind referred to". It will be appreciated that the smooth edge surface of the nut or bolthead makes it difficult, if not impossible, for the nut or bolthead to be rotated with conventional turning tools such as wrenches or conventional spanners. In order to reduce further the possibility of the nut or bolthead being gripped, it is preferred that the edge of the nut or bolthead should be an inclined or arcuate surface of revolution, especially frustoconical or domed shape, into which the said bores extend and the spanner component should be a cap having a recess to receive said edge and into which recess the locating pins project. Said preferred fastening means are commercially available under the trade mark "BARRINUT", in which product the positions of the locating pins and bores are coded so that a specific cap is required to rotate a specific nut or bolthead.
Fastening means of the kind referred to, especially "BARRINUTS" have been successfully employed for retaining wheels on private motor cars and light vans. However, they are not generally acceptable for use on lorries, coaches and other heavy goods and public service vehicles. A principal reason for said lack of acceptance has been the cost of producing such fastening means in a sufficiently heavy duty form to enable conventional tools, especially power wrenches, to be used to tighten the fastening means into a wheel-retaining position. In particular, if the locating pins are not properly located in their respective bores, they can readily be sheared by the torque applied by power wrenches. Accordingly, correct location of the spanner component, especially in the preferred recessed embodiment disclosed above, on the nut or bolthead is essential when using power wrenches. However, such location is not always achieved or maintained with fastening means of prior art design. Moreover, since many goods and public service vehicles do not have fully recessed hubs, as is usual on motor cars and light vans, the nut or bolthead is more accessible to wrenches and other tools and hence more susceptible to unauthorised removal.